Characterization of high-k LaLuO_3 thin film grown on AIGaN/GaN heterostructure by molecular beam deposition

摘要

We report the study of high-dielectric-constant (high-k) dielectric LaLuO_3 (LLO) thin film that is grown on AIGaN/GaN heterostructure by molecular beam deposition (MBD). The physical properties of LLO on AIGaN/GaN heterostrucure have been investigated with atomic force microscopy, x-ray photoelectron spectroscopy, and TEM. It is revealed that the MBD-grown 16nm-thick LLO film is polycrystalline with a thin (～2nm) amorphous transition layer at the LLO/ GaN interface. The bandgap of LLO is derived as 5.3 ± 0.04eV from Ols energy loss spectrum. Capacitance-voltage (C-V) characteristics of a Ni-Au/LLOi-nitride metal-insulator-semiconductor diode exhibit small frequency dispersion (<2%) and reveal a high effective dielectric constant of ～28 for the LLO film. The LLO layer is shown to be effective in suppressing the reverse and forward leakage current in the MIS diode. In particular, the MIS diode forward current is reduced by 7 orders of magnitude at a forward bias of 1V compared to a conventional Ni-Au/III-nitride Schottky diode.